1. Field of the Invention
This invention relates to cartridge type filters and, more particularly, to an assembly of an adapter and a filter which can be used with a wide variety of filtering heads.
2. Description of the Prior Art
Cartridge type filters used for filtering of liquids are manufactured in many shapes and forms. They usually consist of a fixed head and then a removable cartridge which interacts with the head which is permanently or fixedly installed in the piping system in which the filter is installed.
The wide variety of filters that are now marketed and which have been marketed in the past often makes it difficult to obtain the appropriate cartridge that can fit into the head of the filter. Often, filter heads are made that require a specialized cartridge which cannot be easily obtained. An example of such a filter system is shown in U.S. Pat. No. 3,746,171, issued July 17, 1973, to Thomsen. This filter assembly has an unusually shaped filter head that requires a fairly complex and uniquely designed cartridge to mate with the head.
Since it is desirable to be able to use cartridges supplied from a wide variety of sources, both in this system and the other filtering systems presently in use, an adapter is desired that would enable the use of a standard cartridge or a relatively standard cartridge, which adapter could be easily installed on the cartridge and which could then form an assembly that, in turn, could be easily installed in the filter head. It is important that the adapter securely fasten to the cartridge and, in turn, that the adapter can be securely fastened within the filter head to ensure that there will be no failure of the system once the cartridge and adapter are installed. Additionally, it is important that effective sealing be obtained between the cartridge and the adapter and between the adapter and the filter head to prevent any leakage when the system is installed. Also, it is important that installation of the adapter to the cartridge and the adapter to the housing be relatively swift and easy. Further, it is desirable that the adapter be capable of using widely available cartridge type filters such as those similar to the type shown in U.S. Pat. No. 3,954,624, issued May 4, 1976, to Petrucci, and those sold by CUNO Incorporated such as AQUA-PURE 517 (AP517).
Attempts have been made in the past to provide adapters, but they have been less than successful. For example, the patent to Offer, U.S. Pat. No. 3,395,808, shows a relatively simple device but reguires an entire external housing to hold the replacement filter. The patents to Harvey, U.S. Pat. No. 3,743,096, issued July 3, 1973, and to Sanderson, U.S. Pat. No. 3,540,594, show adapters which are not suitable for mounting of cartridge type filters having narrow necks in wide mouthed filter heads.
The Sanderson U.S. Pat. No. 3,540,594, is suitable only for use with a filter head that accepts a very wide type filter cartridge and could not house a narrow filter cartridge. Similarly, Harvey, U.S. Pat. No. 3,743,096, which provides for a flow reversal from inlet to outlet requires an inordinately large amount of room and which could not be used with existing filter heads.